Radio transmission apparatus, radio reception apparatus, and communication method

ABSTRACT

A radio transmission apparatus selects any one group from a plurality of groups each indicating a combination of a plurality of radio reception apparatuses, notifies at least a plurality of radio reception apparatuses belonging to the selected group of an identification number assigned in advance to the selected group, and allocates transmission data addressed to the radio reception apparatuses belonging to the selected group to each of a plurality of frequency resources based on order of the radio reception apparatuses, which is determined in advance in the selected group.

TECHNICAL FIELD

The present invention relates to a radio transmission apparatus, a radioreception apparatus, and a communication method.

BACKGROUND ART

As an advanced standard of IEEE802.11n which is a radio LAN (Local areanetwork) standard that has been widely put into use, an IEEE802.11acstandard has been developed by the IEEE (The Institute of Electrical andElectronics Engineers, Inc.). Currently, standardization efforts for HEW(High efficiency wireless LAN) are to be conducted as a successivestandard of IEEE802.11n/ac. Differently from the past radio LANstandards, not only improvement in peak throughput but also improvementin user throughput are cited as main required conditions in the HEWstandard. It is essential to introduce a highly efficient simultaneousmultiplexing transmission scheme (access scheme) in order to improve theuser throughput.

In standards before the standard of the IEE802.11n, an access scheme ofan autonomous distributed control type called CSMA/CA (Carrier sensemultiple access with collision avoidance) has been adopted as the accessscheme. In the IEEE802.11ac, space division multiple access (SDMA) by amulti-user multiple-input multiple-output (MU-MIMO) technique is newlyadded.

The HEW standard is required to further improve the access scheme forimproving the user throughput. As the highly efficient access scheme,there is Orthogonal Frequency Division Multiple Access (OFDMA). TheOFDMA is a scheme for, by using characteristics of Orthogonal FrequencyDivision Multiplexing (OFDM) which allows enhancement in frequencyefficiency by arranging a large number of orthogonal sub-carriersdensely at intervals of a reciprocal of a signal duration, allocatingany number of sub-carriers (or a frequency band composed of a group ofcontiguous sub-carriers) with good characteristics to each of radioreception apparatus in accordance with reception characteristicsdifferent in the radio reception apparatuses in multipath environments,and thereby further increasing substantial frequency efficiency. It isexpected that the user throughput is improved by introducing the OFDMAto the HEW standard (NPL 1).

CITATION LIST Non Patent Literature

NPL 1: IEEE 11-13/1395r2, “Simultaneous transmission technologies forHEW”, November 2013.

SUMMARY OF INVENTION Technical Problem

However, when the OFDMA is introduced to the radio LAN standard, anaccess point needs to notify each station connected to the access pointof a frequency band (frequency channel or sub-carrier number) to whichdata addressed to each station is allocated. Newly adding informationabout notification of the frequency band to control informationincreases overhead and gives limitation to improvement in the userthroughput.

The invention has been made in view of such circumstances, and an objectthereof is to provide a radio transmission apparatus, a radio receptionapparatus, and a communication method capable of realizing a radio LANsystem in which user throughput is improved by introducing OFDMA whilesuppressing overhead associated with notification of controlinformation.

Solution to Problem

A radio transmission apparatus, a radio reception apparatus, and acommunication method according to the invention for solving theaforementioned problems are as follows.

(1) That is, a radio transmission apparatus of the invention is a radiotransmission apparatus that multiplexes and simultaneously transmitstransmission data addressed to a plurality of radio receptionapparatuses by using OFDMA transmission using a plurality of frequencyresources, in which any one group is selected from a plurality of groupseach indicating a combination of a plurality of radio receptionapparatuses, control information including an identification numberassigned in advance to the selected group is transmitted to at least aplurality of radio reception apparatuses belonging to the selectedgroup, and transmission data addressed to the plurality of radioreception apparatuses belonging to the selected group is allocated toeach of the plurality of frequency resources on the basis of order ofthe radio reception apparatuses, which is determined in advance in theselected group.

(2) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (1), in which the controlinformation further includes information indicating frequency bandwidthsof the plurality of frequency resources to be allocated to thetransmission data addressed to the plurality of radio receptionapparatuses belonging to the selected group.

(3) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (1) or (2), in which for each of theplurality of frequency resources to which the transmission dataaddressed to the plurality of radio reception apparatuses belonging tothe selected group is allocated, transmission signals addressed to theradio reception apparatuses are generated.

(4) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (1) or (2), in which transmissionsignals including all the transmission data which is allocated to theplurality of frequency resources and which is addressed to the pluralityof radio reception apparatuses belonging to the selected group arecollectively generated.

(5) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (1), in which a plurality ofantennas are further included to correspond to MU-MIMO transmission formultiplexing and simultaneously transmitting transmission data addressedto a plurality of radio reception apparatuses by using a plurality ofspace resources, in a case where the OFDMA transmission is used, thetransmission data addressed to the radio reception apparatuses isallocated to each of the plurality of frequency resources andsimultaneously transmitted on the basis of order of the radio receptionapparatuses, which is determined in advance in the selected group, andin a case where the MU-MIMO transmission is used, the transmission dataaddressed to the radio reception apparatuses is allocated to each of theplurality of space resources on the basis of order of the radioreception apparatuses, which is determined in advance in the selectedgroup.

(6) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (5), in which the controlinformation further includes information indicating which one theMU-MIMO transmission and the OFDMA transmission is used as amultiplexing scheme.

(7) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (5), in which a data modulationscheme applied to at least a part of transmission signals including thecontrol information is determined in accordance with which one of theMU-MIMO transmission and the OFDMA transmission is used as amultiplexing scheme.

(8) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (5), in which the controlinformation further includes information indicating frequency bandwidthsof the frequency resources to be allocated to each of the transmissiondata addressed to the plurality of radio reception apparatuses belongingto the selected group, and information indicating the number of thespace resources to be allocated to each of the transmission dataaddressed to the plurality of radio reception apparatuses belonging tothe selected group.

(9) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (5), in which the controlinformation further includes either information indicating frequencybandwidths of the frequency resources to be allocated to each of thetransmission data addressed to the plurality of radio receptionapparatuses belonging to the selected group, or information indicatingthe number of the space resources to be allocated to each of thetransmission data addressed to the plurality of radio receptionapparatuses belonging to the selected group, and the informationindicating the frequency bandwidths of the frequency resources and theinformation indicating the number of the space resources are describedin the same bit field of the control information, which is determined inadvance.

(10) The radio transmission apparatus of the invention is the radiotransmission apparatus according to (1), in which a plurality ofantennas are further included to correspond to MU-MIMO transmission formultiplexing and simultaneously transmitting transmission data addressedto a plurality of radio reception apparatuses by using a plurality ofspace resources, the control information further includes informationindicating frequency bandwidths of the frequency resources to beallocated to each of the transmission data addressed to the plurality ofradio reception apparatuses belonging to the selected group, andinformation indicating the number of the space resources to be allocatedto each of the transmission data addressed to the plurality of radioreception apparatuses belonging to the selected group, and thetransmission data addressed to the radio reception apparatuses isallocated to each of the plurality of frequency resources and theplurality of space resources on the basis of order of the radioreception apparatuses, which is determined in advance in the selectedgroup, the information indicating the frequency bandwidths of thefrequency resources, and the information indicating the number of thespace resources.

(11) A radio reception apparatus of the invention is a radio receptionapparatus that receives a signal which is transmitted from a radiotransmission apparatus and in which transmission data addressed to aplurality of radio reception apparatuses is multiplexed by using OFDMAtransmission using a plurality of frequency resources, in which controlinformation including an identification number of a group is acquiredfrom the received signal, whether or not the radio reception apparatusbelongs to the group corresponding to the identification number isjudged, and in a case where the radio reception apparatus belongs to thegroup as a result of the determination, a frequency resource allocatedto transmission data addressed to the radio reception apparatus isidentified from the plurality of frequency resources on the basis oforder of the radio reception apparatus, which is determined in advancein the group corresponding to the identification number.

(12) The radio reception apparatus of the invention is the radioreception apparatus according to (11), in which the frequency resourceallocated to the transmission data addressed to the radio receptionapparatus is identified from the plurality of frequency resources alsobased on information which is included in the control information andindicates a frequency bandwidth of the frequency resource allocated tothe transmission data addressed to the radio reception apparatus.

(13) The radio reception apparatus of the invention is the radioreception apparatus according to (11), in which the radio transmissionapparatus further includes a plurality of antennas and corresponds toMU-MIMO transmission for multiplexing and simultaneously transmittingtransmission data addressed to a plurality of radio receptionapparatuses by using a plurality of space resources, in a case of usingthe OFDMA transmission, the radio transmission apparatus allocatestransmission data addressed to the radio reception apparatuses to eachof the plurality of frequency resources for simultaneous transmission onthe basis of order of the radio reception apparatuses, which isdetermined in advance in the selected group, and in a case of using theMU-MIMO transmission, the radio transmission apparatus allocates thetransmission data addressed to the radio reception apparatuses to eachof the plurality of space resources for simultaneous transmission on thebasis of order of the radio reception apparatuses, which is determinedin advance in the selected group, the control information includesinformation indicating which one of the OFDMA transmission and theMU-MIMO transmission the radio transmission apparatus uses as amultiplexing scheme, and the multiplexing scheme used by the radiotransmission apparatus is judged on the basis of the control informationand a frequency resource or a space resource allocated to thetransmission data addressed to the radio reception apparatus isidentified.

(14) The radio reception apparatus of the invention is the radioreception apparatus according to (11), in which the radio transmissionapparatus further includes a plurality of antennas and corresponds toMU-MIMO transmission for multiplexing and simultaneously transmittingtransmission data addressed to a plurality of radio receptionapparatuses by using a plurality of space resources, in a case of usingthe OFDMA transmission, the radio transmission apparatus allocatestransmission data addressed to the radio reception apparatuses to eachof the plurality of frequency resources for simultaneous transmission onthe basis of order of the radio reception apparatuses, which isdetermined in advance in the selected group, and in a case of using theMU-MIMO transmission, the radio transmission apparatus allocates thetransmission data addressed to the radio reception apparatuses to eachof the plurality of space resources for simultaneous transmission on thebasis of order of the radio reception apparatuses, which is determinedin advance in the selected group, a data modulation scheme applied bythe radio transmission apparatus to a part of transmission signalsincluding the control information is determined in accordance with whichone of the OFDMA transmission and the MU-MIMO transmission the radiotransmission apparatus uses as a multiplexing scheme, and themultiplexing scheme used by the radio transmission apparatus is judgedon the basis of a data modulation scheme of at least a part of thereceived signal including the control information, and a frequencyresource or a space resource allocated to the transmission dataaddressed to the radio reception apparatus is identified.

(15) The radio reception apparatus of the invention is the radioreception apparatus according to (13) or (14), in which the controlinformation further includes information indicating frequency bandwidthsof the frequency resources to be allocated to the transmission dataaddressed to the plurality of radio reception apparatuses by the radiotransmission apparatus, and information indicating the number of thespace resources to be allocated to the transmission data addressed tothe plurality of radio reception apparatuses by the radio transmissionapparatus, and the transmission data addressed to the radio receptionapparatus is demodulated by the transmission signals on the basis of atleast one of the information indicating the frequency bandwidths of thefrequency resources and the information indicating the number of thespace resources.

(16) The radio reception apparatus of the invention is the radioreception apparatus according to (13) or (14), in which the controlinformation includes either information indicating frequency bandwidthsof the frequency resources to be allocated to the transmission dataaddressed to the plurality of radio reception apparatuses by the radiotransmission apparatus, or information indicating the number of thespace resources to be allocated to the transmission data addressed tothe plurality of radio reception apparatuses by the radio transmissionapparatus, the information indicating the frequency bandwidths of thefrequency resources and the information indicating the number of thespace resources are described in the same bit field of the controlinformation, which is determined in advance, and the frequencybandwidths of the frequency resources or the number of the plurality ofspace resources is acquired from the information which is described inthe bit field, on the basis of the multiplexing scheme used by the radiotransmission apparatus.

(17) The radio reception apparatus of the invention is the radioreception apparatus according to (11), in which the radio transmissionapparatus further includes a plurality of antennas and is able tomultiplex and simultaneously transmit the transmission data addressed tothe plurality of radio reception apparatuses on the basis ofmultiplexing transmission simultaneously using MU-MIMO transmissionusing a plurality of space resources and the OFDMA transmission, thecontrol information further includes information indicating frequencybandwidths of the frequency resources to be allocated to each of thetransmission data addressed to the plurality of radio receptionapparatuses belonging to the selected group by the radio transmissionapparatus, and information indicating the number of the space resourcesto be allocated to each of the transmission data addressed to theplurality of radio reception apparatuses belonging to the selectedgroup, and the frequency resource and the space resource to which thetransmission data addressed to the radio reception apparatus isallocated are acquired on the basis of order of the radio receptionapparatuses, which is determined in advance in the selected group, theinformation indicating the frequency bandwidths of the frequencyresources, and the information indicating the number of the spaceresources.

(18) A communication method of the invention is a communication methodof a radio transmission apparatus that multiplexes and simultaneouslytransmits transmission data addressed to a plurality of radio receptionapparatuses on the basis of OFDMA transmission using a plurality offrequency resources, the communication method includes the steps of:selecting any one group from a plurality of groups each indicating acombination of a plurality of radio reception apparatuses; transmittinga control signal including an identification number assigned in advanceto the selected group to at least a plurality of radio receptionapparatuses belonging to the selected group; and allocating transmissiondata addressed to the plurality of radio reception apparatuses belongingto the selected group to each of the plurality of frequency resources onthe basis of order of the radio reception apparatuses, which isdetermined in advance in the selected group.

(19) A communication method of the invention is a communication methodof a radio reception apparatus that receives a signal which istransmitted from a radio transmission apparatus and in whichtransmission data addressed to a plurality of radio receptionapparatuses is multiplexed by using OFDMA transmission using a pluralityof frequency resources, the communication method includes the steps of:acquiring control information including an identification number of agroup from the received signal; judging whether or not the radioreception apparatus belongs to the group corresponding to theidentification number; and identifying, in a case where the radioreception apparatus belongs to the group as a result of thedetermination, a frequency resource allocated to transmission dataaddressed to the radio reception apparatus from the plurality offrequency resources on the basis of order of the radio receptionapparatus, which is determined in advance in the group corresponding tothe identification number.

Advantageous Effects of Invention

According to the invention, it is possible to realize a radio LAN systemin which user throughput is improved by introducing OFDMA whilesuppressing overhead associated with notification of controlinformation, thus making it possible to greatly improve the userthroughput.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example of a communication system according to theinvention.

FIG. 2 is a schematic block diagram illustrating a configuration exampleof a radio transmission apparatus of the invention.

FIG. 3 illustrates an example of a data frame of the invention.

FIG. 4 is a schematic block diagram illustrating a configuration exampleof a radio reception apparatus of the invention.

FIG. 5A illustrates an example of frequency allocation according to afirst embodiment of the invention.

FIG. 5B illustrates an example of frequency allocation according to thefirst embodiment of the invention.

FIG. 5C illustrates an example of frequency allocation according to thefirst embodiment of the invention.

FIG. 5D illustrates an example of frequency allocation according to thefirst embodiment of the invention.

FIG. 5E illustrates an example of frequency allocation according to athird embodiment of the invention.

FIG. 5F illustrates an example of frequency allocation according to thethird embodiment of the invention.

FIG. 6 illustrates an example of description of a Group ID of theinvention.

FIG. 7 is a sequence chart illustrating an example of communicationaccording to the first embodiment of the invention.

FIG. 8 is a sequence chart illustrating an example of communicationaccording to a second embodiment of the invention.

DESCRIPTION OF EMBODIMENTS 1. First Embodiment

A communication system in the present embodiment includes a radiotransmission apparatus (access point (AP)) and a plurality of radioreception apparatuses (stations (STAs)).

FIG. 1 is a schematic view illustrating an example of downlink of thecommunication system according to a first embodiment of the invention.In the communication system of FIG. 1, there are an AP 1, and a STA 2 toa STA 9 which are connected to the AP 1. The AP 1 performs datatransmission simultaneously to the STAs by Orthogonal Frequency DivisionMultiple Access (OFDMA).

FIG. 2 is a block diagram illustrating an example of a configuration ofthe AP 1 according to the first embodiment of the invention. Asillustrated in FIG. 2, the AP 1 includes a higher layer unit 101, acontrol unit 102, a transmission unit 103, a reception unit 104, and anantenna 105.

The higher layer unit 101 performs processing in a medium access control(MAC) layer and the like. The higher layer unit 101 generatesinformation for performing control of the transmission unit 103 and thereception unit 104 and outputs the information to the control unit 102.The control unit 102 controls the higher layer unit 101, thetransmission unit 103, and the reception unit 104.

The transmission unit 103 further includes a physical channel signalgeneration unit 1031, a frame configuration unit 1032, a control signalgeneration unit 1033, and a radio transmission unit 1034. The physicalcannel signal generation unit 1031 generates baseband signals to betransmitted by the AP 1 to the STAs. The signals generated by thephysical channel signal generation unit 1031 include TFs (Trainingfields) used by the STAs for channel estimation and data transmitted ina MSDU (MAC service data unit). Note that, an example in which thebaseband signals to be transmitted to the STA 2 to the STA 9 aregenerated is indicated because the number of the STAs is eight in FIG.1, but the present embodiment is not limited thereto.

The frame configuration unit 1032 multiplexes a signal generated by thephysical channel signal generation unit 1031 and a signal generated bythe control signal generation unit 1033, and configures a data frame ofthe baseband signal actually transmitted by the AP 1. FIG. 3 is aschematic view illustrating an example of the data frame generated bythe frame configuration unit 1032 according to the present embodiment.The data frame includes reference signals such as a L-STF (Legacy shorttraining filed), a L-LTF (Legacy long training filed), a VHT-STF (Veryhigh throughput-short training field), and a VHT-LTF (Very highthroughput-long training field), control information such as a L-SIG(Legacy-signal), a VHT-SIG-A (Very high throughput-signal-A), and aVHT-SIG-B (Very high throughput-signal-B), and a Data (data) portion.Hereinafter, time intervals in which the reference signals, the controlinformation, and the data portion are transmitted in the data frame arerespectively referred to as a preamble channel, a control channel, and adata channel. In the present embodiment, control information generatedby the control signal generation unit 1033 will be described below.

The radio transmission unit 1034 performs processing for converting thebaseband signals generated by the frame configuration unit 1032 intoradio frequency (RF) band signals. The processing performed by the radiotransmission unit 1034 includes digital/analog conversion, filtering,frequency conversion from the baseband to the RF band, and the like.

The antenna 105 transmits signals generated by the transmission unit 103to the STAs.

The AP 1 also has a function of receiving signals transmitted from theSTAs. The antenna 105 receives the signals transmitted from the STAs andoutputs the signals to the reception unit 104.

The reception unit 104 includes a physical channel signal demodulationunit 1041 and a radio reception unit 1042. The radio reception unit 1042converts RF band signals input from the antenna 105 to baseband signals.The processing performed by the radio reception unit 1042 includesfrequency conversion from the RF band to the baseband, filtering,analog/digital conversion, and the like. The processing performed by thereception unit 104 may include a function (carrier sense) of measuringperipheral interference in a specific frequency band to secure thefrequency band.

The physical channel signal demodulation unit 1041 demodulates thebaseband signals output by the radio reception unit 1042. The signalsdemodulated by the physical channel signal demodulation unit 1041 aresignals transmitted in uplink by the STA 2 to the STA 9, and have aframe configuration similar to that of the data frame generated by theframe configuration unit 1032. Thus, the physical channel signaldemodulation unit 1041 is able to demodulate the uplink data by the datachannel on the basis of control information transmitted by the controlchannel of the data frame. Further, the physical channel signaldemodulation unit 1041 may include a carrier sense function.

FIG. 4 is a block diagram illustrating a configuration example of theSTA 2 to the STA 9 according to the present embodiment. As illustratedin FIG. 4, each of the STA 2 to the STA 9 includes a higher layer unit201, a control unit 202, a transmission unit 203, a reception unit 204,and an antenna 205.

The higher layer unit 201 performs processing of a MAC layer and thelike. The higher layer unit 201 generates information for performingcontrol of the transmission unit 203 and the reception unit 204 andoutputs the information to the control unit 202.

The antenna 205 receives a signal transmitted by the AP 1 and outputsthe signal to the reception unit 204.

The reception unit 204 includes a physical channel signal demodulationunit 2041, a control information monitoring unit 2042, and a radioreception unit 2043. The radio reception unit 2043 converts a RF bandsignal input from the antenna 205 into a baseband signal. The processingperformed by the radio reception unit 2043 includes frequency conversionfrom the RF band to the baseband, filtering, analog/digital conversion,and the like.

The control information monitoring unit 2042 performs monitoring of thecontrol channel for the baseband signal output by the radio receptionunit 2043 and acquires control information to be transmitted by the AP 1to the STA 2 to the STA 9. The control information includes commoncontrol information (for example, VHT-SIG-A) common in the STAs andspecific control information (for example, VHT-SIG-B) different for eachof the STAs.

The physical channel signal demodulation unit 2041 demodulates thesignal of the data channel on the basis of the control informationacquired by the control information monitoring unit 2042.

Each of the STA 2 to the STA 9 also has a function of transmitting asignal. The antenna 205 transmits a RF band signal generated by thetransmission unit 203 to the base-station apparatus 1.

The transmission unit 203 includes a physical channel signal generationunit 2031 and a radio transmission unit 2032. The physical channelsignal generation unit 2031 generates a baseband signal to betransmitted by each of the STA 2 to the STA 9 to the AP 1. The signalgenerated by the physical channel signal generation unit 2031 has asimilar configuration to that of the data frame generated by the frameconfiguration unit 1032 of the AP 1.

The radio transmission unit 2032 converts the baseband signal generatedby the physical channel signal generation unit 2031 into a RF bandsignal. The processing performed by the radio transmission unit 2032includes digital/analog conversion, filtering, frequency conversion fromthe baseband to the RF band, and the like.

In the present embodiment, it is considered that the AP 1 performs datatransmission by the OFDMA simultaneously to the STA 2 to the STA 9. FIG.5A is a schematic view illustrating an example of frequency allocationto the STA 2 to the STA 9 according to the present embodiment. It isconsidered that the AP 1 is able to use a frequency bandwidth of 80 MHzand allocates 20 MHz to each of the STAs. That is, the AP 1 divides theusable frequency bandwidth of 80 MHz into four channels (ch) each having20 MHz and allocates one STA to each of the channels.

The AP 1 needs to notify the STAs in which frequency band (asub-carrier, a sub-band as a bundle of a plurality of sub-carriers, or afrequency resource) the data channel is arranged. Thus, the AP 1according to the present embodiment applies a function called a Group IDadopted by the IEEE802.11ac.

The Group ID used in the IEEE802.11ac is one of common controlinformation included in the VHT-SIG-A transmitted in the control channelby the AP 1 and is an identification number (index) for identifying agroup which is decided in advance by the AP 1 and indicates acombination of STAs subjected to spatial multiplexing by the MU-MIMO. Byreading the Group ID, each of the STAs is able to judge whether or notthe STA participates in the MU-MIMO transmission, and when participatingtherein, judge in what number of space resource the STA is multiplexed.Here, generally, the AP 1 including N antennas is able to spatiallymultiplex N STAs or N pieces of data at most, and the space resourcerefers to a layer or a data stream in which N STAs or N pieces of datathat can be spatially multiplexed by the AP 1 are arranged.

Thus, the control signal generation unit 1033 of the AP 1 according tothe present embodiment determines a value of the Group ID in accordancewith frequency allocation to the STAs. FIG. 6 is a table indicating anexample of the Group ID according to the present embodiment. The AP 1according to the present embodiment determines in advance a group ofSTAs to be described in the Group ID and shares the content thereofbetween the AP 1 and each of the STAs in advance. In addition, the AP 1may change a group of STAs described in the Group ID as appropriate andperform sharing with the STAs each time. The Group ID according to thepresent embodiment represents an index indicating a combination (group)of STAs participating in OFDMA transmission, which is determined by theAP 1 in advance. An order of STAs described in a field of the belongingSTA indicates to which channel each of the STAs is allocated. Forexample, in FIG. 6, a number 2 of the Group ID indicates that the STA 3,the STA 2, the STA 4, and the STA 5 participate in (are included, belongto) the OFDMA transmission. It is further indicated that the STA 3, theSTA 2, the STA 4, and the STA 5 are respectively allocated to the firstchannel, the second channel, the third channel, and the fourth channel.Thus, when the AP 1 considers frequency allocation to the STAs asillustrated in FIG. 5A, the control signal generation unit 1033 maygenerate control information for specifying a number 1 as the Group ID.

FIG. 7 is a sequence chart illustrating an example of communicationaccording to the present embodiment. First, the higher layer unit 201 ofthe AP 1 determines a combination of STAs that participate in the OFDMAtransmission (step S701). Note that, in the communication according tothe present embodiment, a step of determining a group of STAs to bedescribed in the Group ID, a step of sharing, with the STAs, content ofthe description of the determined Group ID, and a step of updating thecontent of the description of the group ID may be provided by the AP 1before step S701. Then, on the basis of the determination of the higherlayer unit 201, the control signal generation unit 1033 determines avalue of the Group ID and outputs the value to the frame configurationunit 1032 (step S702). Note that, the higher layer unit 201 maydetermine a combination of STAs to be multiplexed on the basis of thecontent of the description of the current Group ID. Next, the frameconfiguration unit 1032 generates a data frame that includes controlinformation (for example, VHT-SIG-A) including the value of the Group IDgenerated by the control signal generation unit 1033 (step S703). Theradio transmission unit 1034 then generates a transmission signal in aRF band, and the AP 1 transmits a signal to each of the STAs through theantenna 105 (step S704). The control information monitoring unit 2042 ofthe STA reads the Group ID from the signal which is transmitted by thecontrol channel in the data frame transmitted from the AP 1, and judgeswhether or not the STA participates in the OFDMA transmission (stepS705). When the STA judges that the STA (here, the STA 2 to the STA 5)participates in the OFDMA transmission, the physical channel signalgeneration unit 2031 specifies a frequency, in which data of the STA isarranged, from the Group ID, and demodulates data addressed to the STAwith a signal transmitted from the AP 1 by the data channel of thefrequency (step S706). When the STA judges that the STA (here, the STA 6to the STA 9) does not participate in the OFDMA transmission, thephysical channel signal generation unit 2031 does not performdemodulation of the signal (step S707). The above is an example of thecommunication according to the present embodiment.

Note that, FIG. 5A illustrates an example in which the AP 1 allocates abandwidth of 20 MHz equally to each of the STAs. The AP 1 according tothe present embodiment is also able to allocate a frequency bandwidthunequally to each of the STAs. FIG. 5B is a schematic view illustratinganother example of frequency allocation to the STA 2 to the STA 9according to the present embodiment. The AP 1 is able to use thefrequency bandwidth of 80 MHz and allocates the bandwidth of 40 MHz tothe STA 2 and the bandwidth of 20 MHz to each of the STA 4 and the STA5. At this time, the AP 1 notifies the STAs of information indicatingthe frequency bandwidth allocated to each of the STAs.

As the information indicating the frequency bandwidth allocated to theSTA, the control signal generation unit 1033 generates information (thenumber of multiplexing channels) indicating how many channels areallocated with the bandwidth of 20 MHz as one channel. When the AP 1considers frequency allocation as illustrated in FIG. 5B, the controlsignal generation unit 1033 may specify the number 1 as the Group ID andnotify the STA 2 of 2, the STA 3 of 0, and the STA 4 and the STA 5 of 1as the number of multiplexing channels. Since the number of multiplexingchannels, which is generated by the control signal generation unit 1033,is information described in the VHT-SIG-A, the STA is also able to graspthe number of multiplexing channels allocated to other STAs.

When such control information is generated by the control signalgeneration unit 1033, for example, the STA 2 is able to grasp that theSTA 2 participates in the OFDMA transmission, receives allocation fromthe first channel, and receives allocation of two channels (that is, thebandwidth of 40 MHz) in total.

On the other hand, while the STA 3 recognizes that the STA 3participates in the OFDMA transmission, the STA 3 is able to recognizethat data is not transmitted to the STA 3 because the number ofmultiplexing channels is 0.

The STA 4 is able to grasp that the STA 4 participates in the OFDMAtransmission, is arranged in the third place, and one channel (that is,the bandwidth of 20 MHz) is allocated to the STA 4. Further, the STA 4is also able to grasp that there are two STAs allocated to channelsbefore that of the STA 4 and the number of the allocated channels is two(that is, the bandwidth of 40 MHz) in total. Thus, the STA 4 is able tograsp that STA 4 is allocated to the third channel with the bandwidth of20 MHz. Similarly, the STA 5 is able to grasp that the STA 5 isallocated to the fourth channel with the bandwidth of 20 MHz.

Note that, the AP 1 is also able to notify each of the STAs in advanceof a usable frequency bandwidth and a frequency thereof. In this case,the STA is able to grasp from which frequency the frequency allocationby the AP 1 is started, thus making it possible to more easily grasp theallocated frequency of the STA.

As the information indicating the frequency bandwidth allocated to theSTA, the control signal generation unit 1033 may generate informationdirectly indicating the frequency bandwidth (or the number ofsub-carriers) allocated to the STA instead of the number of multiplexingchannels. When the AP 1 notifies the STA of the information indicatingthe frequency bandwidth allocated to the STA, the value of the Group IDgenerated by the control signal generation unit 1033 is not always onedefined value. For example, the frequency allocation as illustrated inFIG. 5B is performed, the control signal generation unit 1033 is able tosend signaling of any Group ID, which indicates a group in which the STA2, the STA 4, and the STA 5 are described in this order, to each of theSTAs.

The frequency bandwidth usable by the AP 1 may be a frequency bandwidthother than 80 MHz and does not need to be always a contiguous frequency.FIG. 5C illustrates an example of frequency allocation in a case wherethe AP 1 is able to use the incontiguous frequency band with thebandwidth of 160 MHz in total. Here, it is assumed that the AP 1notifies each of the STAs in advance of a usable frequency bandwidth anda frequency thereof. Also when the AP 1 performs frequency allocation asillustrated in FIG. 5C, the control signal generation unit 1033 mayspecify the number 1 as the Group ID and notify the STA 2 of 2, the STA3 and the STA 4 of 1, and the STA 5 of 4 as the number of multiplexingchannels.

In the schematic view of frequency allocation by the AP 1 illustrated inFIG. 5A, it is assumed that data signals addressed to each of the STAsare subjected to OFDM modulation separately. That is, the frameconfiguration unit 1032 of the AP 1 generates four OFDM signals eachhaving an occupied bandwidth (here, including a guard band forsuppressing out-of-band radiation) of 20 MHz and arranges each of themin the frequency allocated to each of the STAs (hereinafter, referred toas individual arrangement). In this case, the STA is required todemodulate only the OFDM signal transmitted in the frequency allocatedto the STA, thus making it possible to reduce burden on demodulation ofthe OFDM signal by the STA.

On the other hand, the frame configuration unit 1032 of the AP 1 maygenerate one OFDM signal that occupies a whole of the usable frequencybandwidth (in the case of FIG. 5A, 80 MHz) (hereinafter, referred to ascollective arrangement). FIG. 5D is a schematic view illustratinganother example of frequency allocation to the STA 2 to the STA 5according to the present embodiment. At this time, since the frameconfiguration unit 1032 allocates each sub-carrier of the generated OFDMsignal to each of the STAs, the guard band for suppressing out-of-bandradiation, which is required in the individual arrangement, is able tobe reduced, thus making it possible to improve frequency efficiency. Inthis case, it is needless to say that the number of sub-carriers to beallocated to the STAs by the AP 1 may not be equal. Further, the AP 1may perform control so as to perform the individual arrangement for apart of the frequency while performing the collective arrangement.

Whether to perform the individual arrangement or the collectivearrangement by the AP 1 may be determined in advance between the AP 1and each of the STAs or may be notified to each of the STAs by usingcommon control information such as the VHT-SIG-A. The STA may blindlyestimate whether to be the individual arrangement or the collectivearrangement. For example, in the case of the individual arrangement, bymeasuring power of the frequency serving as the guard band, the STA isable to judge whether to be the individual arrangement (when the powerof the frequency is smaller than power of other frequencies) or thecollective arrangement (when the power of the frequency is equal toother frequencies). Note that, when the AP 1 performs the collectivearrangement, an OFDM signal including a null sub-carrier correspondingto a carrier hole or a guard band may be generated similarly to theindividual arrangement.

According to a method of the present embodiment, since the AP 1 is ableto notify each of the STAs of an allocated frequency channel by using avalue of the Group ID, it is possible to realize OFDMA transmissionwhile suppressing overhead associated with the notification.

2. Second Embodiment

In the present embodiment, the AP 1 also corresponds to multiplexingtransmission by MU-MIMO transmission in addition to the OFDMAtransmission. Note that, an outline of the communication system, aconfiguration of the AP 1, and configurations of the STAs 2 to 9 in thepresent embodiment are the same as those of the first embodiment.

In the present embodiment, when performing data transmissionsimultaneously to the STAs, the higher layer unit 101 of the AP 1 judgesin advance whether to perform the OFDMA transmission or the MU-MIMOtransmission. A reference for changing a multiplexing transmissionscheme (a multiplexing scheme, multiplexing transmission, simultaneousmultiplexing transmission, an access scheme) by the higher layer unit101 is not limited, but may be determined, for example, on the basis ofreception quality of the STAs. Further, in order for the AP 1 to performthe MU-MIMO transmission, channel state information (CSI) between the AP1 and each of the STAs is required. The AP 1 may perform control so asto perform the MU-MIMO transmission when grasping the CSI between the AP1 and each of the STAs by control information or the like notified fromthe STAs and perform the OFDMA transmission when not grasping the CSI.

The control signal generation unit 1033 determines a value of the GroupID in accordance with a combination of STAs subjected to simultaneoustransmission. In this case, the value of the Group ID generated by thecontrol signal generation unit 1033 does not change between a case wherethe AP 1 performs the MU-MIMO transmission and a case where the AP 1performs the OFDMA transmission. For example, in a case where the STA 2,the STA 3, the STA 8, and the STA 5 are multiplexed by the OFDMAtransmission when the Group ID provided in FIG. 6 is used, the controlsignal generation unit 1033 specifies a number 33 as the Group ID. Onthe other hand, also in a case where the AP 1 multiplexes the STA 2, theSTA 3, the STA 8, and the STA 5 by the MU-MIMO transmission, the number33 is specified as the Group ID.

Note that, the higher layer unit 101 of the AP 1 may determine themultiplexing transmission scheme after determining a combination ofSTAs.

Since the AP 1 uses the same Group ID regardless of the access scheme,the STA needs to judge whether the STA participates in the OFDMAtransmission or participates in the MU-MIMO transmission. In the presentembodiment, the AP 1 is able to send signaling, which indicates whetherthe AP 1 performs the OFDMA transmission or the MU-MIMO transmission, toeach of the STAs by control information such as the VHT-SIG-A.

Control may be performed so that, with a specific combination of datamodulation schemes used in VHT-SIG-A transmission, each of the STAsjudges the access scheme used by the AP 1. For example, it is determinedin advance such that the AP 1 uses OBPSK (Offset binary phase shiftkeying) in the first OFDM symbol of the VHT-SIG-A and BPSK for thesecond OFDM symbol in the case of performing the OFDMA transmission, anduses the BPSK for the first OFDM symbol and the OBPSK for the secondsymbol in the case of performing the MU-MIMO transmission, so that theSTA is able to judge whether the AP 1 performs the OFDMA transmission orthe MU-MIMO transmission on the basis of power of a real part and animaginary part of contiguous two OFDM symbols.

The CSI between the AP 1 and each of the STAs is required when the AP 1performs the MU-MIMO transmission. As a method for acquiring the CSI bythe AP 1, a method for transmitting a packet called NDP (Null datapacket) announcement by which the AP 1 indicates a feedback request ofthe CSI to each of the STAs is defined in the IEEE802.11n/ac. Thus, theSTA may judge that the packet which is delivered to the STA in a fixedtime period after receiving the NDP announcement is transmitted by theAP 1 by means of the MU-MIMO transmission. A value of the fixed timeperiod may be determined in advance between the AP 1 and each of theSTAs or the AP 1 may include the value in the NDP announcement. Notethat, the AP 1 may include information, which indicates that the OFDMAtransmission is performed to the STA, in the NDP announcement or maynotify the STA that the OFDMA transmission is performed by setting thevalue of the fixed time period as 0.

The STA judges whether the AP 1 performs the OFDMA transmission or theMU-MIMO transmission on the basis of the received data frame, and thenjudges, from the value of the Group ID, in which radio resource(frequency resource or space resource) data addressed to the STA isarranged. For example, considered is a case where the number 1 of theGroup ID described in FIG. 6 is notified to the STA 3. When the AP 1performs the OFDMA transmission, the STA 3 is able to judge thattransmission is performed to the STA 3 with the second frequencyresource (in the case of FIG. 5A, the second channel). On the otherhand, when the AP 1 performs the MU-MIMO transmission, the STA 3 is ableto judge that transmission is performed to the STA 3 with the secondspace resource.

FIG. 8 is a sequence chart indicating an example of communicationaccording to the present embodiment. First, the higher layer unit 101 ofthe AP 1 determines a combination of STAs subjected to simultaneoustransmission and a multiplexing scheme (OFDMA transmission or MU-MIMOtransmission) to be used (step S801). The control signal generation unit1033 of the AP 1 then determines a value of the Group ID in accordancewith the combination of the STAs, which is determined by the higherlayer unit 101 (step S802). Further, the frame configuration unit 1032generates a data frame that includes control information (for example,VHT-SIG-A) including the value of the Group ID generated by the controlsignal generation unit 1033 (step S803). Note that, processing (forexample, addition of control information, application of a specificcombination of data modulation schemes) by which each of the STAs isable to judge the multiplexing scheme performed for the STA by the AP 1is performed by the frame configuration unit 1032 for the data framegenerated by the frame configuration unit 1032 according to the presentembodiment. Then, the radio transmission unit 1034 generates atransmission signal in the RF band, and the AP 1 transmits the signal tothe STA through the antenna 105 (step S804). The control informationmonitoring unit 2042 of the STA judges, from the data frame transmittedfrom the AP 1, a multiplexing scheme performed by the AP 1 to the STA(step S805). The control information monitoring unit 2042 then reads aGroup ID from the signal transmitted by the control channel and judgeswhether or not the STA participates in the multiplexing transmission(step S806). When judging that the STA (here, the STA 2 to the STA 5)participates in the multiplexing transmission, the physical channelsignal generation unit 2031 specifies, from the Group ID, a radioresource in which data of the STA is arranged, and demodulates dataaddressed to the STA with the signal transmitted from the AP 1 by thedata channel of the radio resource (step S807). When judging that theSTA (here, the STA 6 to the STA 9) does not participate in themultiplexing transmission, the physical channel signal generation unit2031 does not demodulate the signal (step S808). Note that, theprocessing of step S805 and the step S806 may be reversed in order, andin such a case, when judging that the STA does not participate in themultiplexing transmission at step S806, the judgment of the multiplexingscheme at step S805 is able to be omitted. The above is an example ofthe communication according to the present embodiment.

The control signal generation unit 1033 according to the presentembodiment may further generate information (for example, a frequencybandwidth or the number of multiplexing channels) indicating the numberof frequency resources allocated to the STAs and information (forexample, the number of streams for spatial multiplexing) indicating thenumber of space resources allocated to the STAs. At this time, controlmay be performed so that the control signal generation unit 1033generates both the number of multiplexing channels and the number ofstreams for spatial multiplexing or generates only one of theinformation on the basis of the multiplexing transmission schemedetermined by the higher layer unit 101.

When the control signal generation unit 1033 generates only one of thenumber of multiplexing channels and the number of streams for spatialmultiplexing, the control signal generation unit 1033 may describe theinformation in the same bit field of control information. The controlinformation monitoring unit 2042 of the STA is able to judge, beforereading the control information, the multiplexing transmission schemeperformed by the AP 1 for the STA, and is thus able to judge whether theinformation described in the bit field is the number of frequencyresources or the number of space resources.

According to the method described above, the AP 1 is able to notify theSTA of condition of resource allocation by the Group ID also in a radioLAN through which the AP 1 selectively performs the OFDMA transmissionand the MU-MIMO transmission, thus making it possible to improve userthroughput while minimizing an increase in overhead.

3. Third Embodiment

In the present embodiment, the AP 1 performs multiplexing transmissionusing the OFDMA transmission and MU-MIMO transmission simultaneously.Note that, an outline of the communication system, a configuration ofthe AP 1, and configurations of the STAs 2 to 9 in the presentembodiment are the same as those of the first embodiment.

In the present embodiment, when performing data transmissionsimultaneously to the STAs, the higher layer unit 101 of the AP 1 judgesin advance whether to perform the OFDMA transmission, perform theMU-MIMO transmission, or simultaneously perform the OFDMA transmissionand the MU-MIMO transmission. A case where the AP 1 simultaneouslyperforms the OFDMA transmission and the MU-MIMO transmission will bedescribed below.

FIG. 5E is a schematic view illustrating an example of frequencyallocation to the STA 2 to the STA 9 according to the presentembodiment. It is assumed that the AP 1 performs multiplexingtransmission for the STA 2 to the STA 5, allocates a bandwidth of 40 MHzto each of the STAs, and further spatially multiplexes the STA 2 and theSTA 4 and spatially multiplexes the STA 3 and the STA 5.

The control signal generation unit 1033 determines a value of the GroupID in accordance with a combination of STAs subjected to simultaneoustransmission. At this time, the value of the Group ID generated by thecontrol signal generation unit 1033 is determined merely by thecombination of STAs participating in simultaneous transmission and doesnot depend on condition of multiplexing of the STAs. For example, in acase where the AP 1 uses the Group ID illustrated in FIG. 6, even whenthe AP 1 allocates the STA 5 to the frequency, to which the STA 2 andthe STA 3 are allocated, under the allocation condition as illustratedin FIG. 5E, the control signal generation unit 1033 generates the number1 as the Group ID.

In the present embodiment, information (for example, the frequencybandwidth or the number of multiplexing channels) indicating the numberof frequency resources allocated to each of the STAs is furthergenerated. Here, the information indicating the number of frequencyresources, which is generated by the control signal generation unit1033, does not depend on the condition of multiplexing of the STAssimilarly to the Group ID, and merely indicates the number of frequencyresources allocated to the STAs. In the case of FIG. 5E, when thecontrol signal generation unit 1033 notifies the number of multiplexingchannels as the information indicating the number of frequencyresources, values of 2, 2, 2, and 2 are respectively generated for theSTA 2, the STA 3, the STA 4, and the STA 5.

In the present embodiment, the AP 1 notifies each of the STAs in advanceof a usable frequency bandwidth and a frequency thereof. In the case ofFIG. 5E, the AP 1 notifies the STA in advance that a frequency bandwidthof 80 MHz is usable. That is, the control signal generation unit 1033 ofthe AP 1 according to the present embodiment generates the Group ID, theinformation indicating the number of frequency resources, and theinformation indicating the frequency bandwidth usable by the AP 1 andthe frequency thereof. Note that, since signal processing of othercomponent devices of the AP 1 is similar to those of the firstembodiment and the second embodiment, description thereof will beomitted.

On the other hand, the STA needs to judge in which data channel of adata frame transmitted from the AP 1 transmission data addressed to theSTA is included and with which radio resource the data frame istransmitted. From the value of the Group ID that is included in controlinformation transmitted by a control channel of the data frametransmitted from the AP 1, the control information monitoring unit 2042of the STA judges whether the STA participates in multiplexingtransmission. When the STA is able to judge that the STA participates inthe multiplexing transmission, the STA judges the radio resource, towhich the transmission data of the STA is allocated, on the basis of theinformation indicating the number of frequency resources included in thecontrol information and the information indicating the frequencybandwidth usable by the AP 1 and the frequency thereof.

Here, it is assumed that the AP 1 performs resource allocation asillustrated in FIG. 5E and notifies each of the STAs that the Group ID(refer to FIG. 6) is the number 1, the number of frequency resources(the number of multiplexing channels with a bandwidth of 20 MHz as onechannel) for each of the STAs is 2, and further a frequency band of 80MHz is usable.

First, the control information monitoring unit 2042 of the STA sets twointernal variables of a frequency resource counter and a space resourcecounter, and initializes them to 1. Then, each of the counters isincreased (incremented) on the basis of the information (here, thenumber of multiplexing channels with the bandwidth of 20 MHz as onechannel) indicating the number of frequency resources notified from theAP 1. Note that, the frequency resource counter may be controlled on thebasis of the number of sub-carriers to which transmission data to theSTA is allocated.

First, the STA 2 described first in the Group ID is able to judge thatthe transmission data addressed to the STA 2 is allocated to thebandwidth of 40 MHz from the beginning of the frequency usable by the AP1. Since the space resource counter is 1, the STA 2 is able to judgethat the transmission data addressed to the STA 2 is arranged in thefirst place of the space resource. At this time, the frequency resourcecounter of STAs arranged in other Group IDs is increased by 2.

Further, since the frequency resource counter and the space resourcecounter of the STA 3 are respectively 3 and 1, the STA 3 is able tojudge that the frequency resource in which the transmission dataaddressed to the STA 3 is arranged is 40 MHz in the last half of thebandwidth of 80 MHz usable by the AP 1 and the space resource is in thefirst place. At this time, the frequency resource counter of STAsarranged in other Group IDs is increased by 2.

Then, the frequency resource counter of the STA 4 is 5 and is found tobe exceeding the number of multiplexing channels (4 in the case of FIG.5E) usable by the AP 1, so that the space resource counter is increasedby 1 and the frequency resource counter is decreased by 4 (the number ofmultiplexing channels usable by the AP 1). This processing is similarlyperformed for other STAs. The STA 4 is able to judge that the frequencyresource in which the transmission data addressed to the STA 4 isarranged is the first 40 MH of the bandwidth of 80 MHz usable by the AP1 and the space resource is in the second place. At this time, thefrequency resource counter of STAs arranged in other Group IDs isincreased by 2.

Lastly, since the frequency resource counter and the space resourcecounter of the STA 5 are respectively 3 and 2, the STA 5 is able tojudge that the frequency resource in which the transmission dataaddressed to the STA 5 is arranged is 40 MHz in the last half of thebandwidth of 80 MHz usable by the AP 1 and the space resource is in thesecond place. In this manner, the STA is able to judge the radioresource, in which the transmission data addressed to the STA isarranged, from the value of the Group ID notified from the AP 1, theinformation indicating the number of frequency resources, and theinformation indicating the frequency bandwidth usable by the AP 1. Thatis, the AP 1 according to the present embodiment performs processing forsequentially allocating the space resource from the first place and alsothe frequency resource from the first place in accordance with order ofthe STAs described in the Group ID, and then allocating the frequencyresource to the STAs preferentially.

Note that, the AP 1 may notify the STAs in advance of the maximum numberof usable space resources and perform allocation from the space resourceto the STAs preferentially. That is, the STAs preferentially increasethe space resource counter.

The AP 1 according to the present embodiment may further notify the STAsof information indicating the number of space resources allocated to theSTAs. FIG. 5F is a schematic view illustrating another example offrequency allocation to the STA 2 to the STA 9 according to the presentembodiment. After performing the frequency allocation similar to that ofFIG. 5E, the AP 1 allocates two space resources to the STA 2. At thistime, the control signal generation unit 1033 generates the number 1 asthe Group ID, 2 for each of the STAs as the information indicating thenumber of frequency resources, and 2 for the STA 2, 3 for the STA 3, and1 for each of the STA 4 and the STA 5 as the information indicating thenumber of space resources.

The control information monitoring unit 2042 of each of the STAs setstwo internal variables of a frequency resource counter and a spaceresource counter, and when the information indicating the number ofspace resources is notified from the AP 1, the space resource counter isset for each frequency resource.

The STA 2 is able to judge that the transmission data addressed to theSTA 2 is allocated to the 40 MHz from the beginning of the frequencybandwidth usable by the AP 1. Since the space resource counter for thefrequency resource is 1, the STA 2 is able to judge that thetransmission data addressed to the STA 2 is arranged from the firstplace to the second place of the space resource. At this time, thefrequency resource counter of STAs arranged in other Group IDs isincreased by 2 and the space resource counter for the frequency resourceis increased by 2.

Further, since the frequency resource counter and the space resourcecounter of the STA 3 are respectively 3 and 1, the STA 3 is able tojudge that the frequency resource in which the transmission dataaddressed to the STA 3 is arranged is 40 MHz in the last half of thebandwidth of 80 MHz usable by the AP 1 and the space resource is in thefirst place. At this time, the frequency resource counter of STAsarranged in other Group IDs is increased by 2 and the space resourcecounter for the frequency resource is increased by 1.

Then, the frequency resource counter of the STA 4 is 5 and is found tobe exceeding the number of multiplexing channels (4 in the case of FIG.5E) usable by the AP 1, so that the STA 4 judges that the STA 4participates in the MU-MIMO transmission. In this case, the frequencycounter of the STA 4 is reset so as to allow allocation from thefrequency resource whose space resource counter is the smallest. In FIG.5F, at a time when the STA 4 judges the radio resource allocated to theSTA 4, the third and fourth frequency resources have the smallest numberof space resources, so that the frequency resource counter is set to 3.Thus, the STA 4 is able to judge that the frequency resource in whichthe transmission data addressed to the STA 4 is arranged is 40 MHz inthe last half of the bandwidth of 80 MHz usable by the AP 1 and thespace resource is in the second place. At this time, the frequencyresource counter of STAs arranged in other Group IDs is increased by 2and the space resource counter for the frequency resource is increasedby 1.

Further, since the frequency resource counter of the STA 5 is 5 and thespace resource counter of all the frequency resources is 3, it is foundthat the number of multiplexing channels (4 in the case of FIG. 5E)usable by the AP 1 is exceeded, so that the STA 5 is able to judge thatthe frequency resource in which the transmission data addressed to theSTA 5 is arranged is the first 40 MH of the bandwidth of 80 MHz usableby the AP 1 and the space resource is in the third place. In thismanner, when the AP 1 notifies each of the STAs of the informationindicating the number of space resources, the STA is able to judge theradio resource in which the transmission data addressed to the STA isarranged even in a case where different number of space resources areallocated to each of the STAs.

When considering the method of the present embodiment differently, itcan be said that the higher layer unit 101 of the AP 1 is desired todetermine allocation of the radio resource to the STA so that the STA isable to judge the radio resource, to which the transmission dataaddressed to the STA is allocated, from the two internal variables ofthe frequency resource counter and the space resource counter providedin the control information monitoring unit 2042 of the STA and thecontrol information notified by the control signal generation unit 1033.

Note that, in the present embodiment, though the control informationmonitoring unit 2042 of the STA judges the radio resource, in which thetransmission data addressed to the STA is arranged, by using theinternal variables called the frequency resource counter and the spaceresource counter, a method for judging the radio resource by the controlinformation monitoring unit 2042 is not limited thereto as long as anequivalent effect is achieved.

According to the method of the present embodiment, the AP 1 is able toapply, by using the Group ID, the multiplexing transmissionsimultaneously using the OFDMA transmission and the MU-MIMO transmissionto the STAs, so that it is possible to improve user throughput whilesuppressing overhead associated with notification of controlinformation.

[4. Common in all Embodiments]

Note that, a program which runs in the radio transmission apparatus andthe radio reception apparatus according to the invention is a programthat controls a CPU and the like (program that causes a computer tofunction) such that the functions in the aforementioned embodimentsconcerning the invention are realized. The pieces of information handledby the apparatuses are temporarily accumulated in a RAM during theprocessing thereof, and then stored in various ROMs and HDDs and read,corrected, and written by the CPU when necessary. A recording mediumthat stores the program therein may be any of a semiconductor medium(for example, a ROM, a nonvolatile memory card or the like), an opticalrecording medium (for example, a DVD, an MO, an MD, a CD, a BD or thelike), a magnetic recording medium (for example, a magnetic tape, aflexible disc or the like), and the like. Moreover, there is also a casewhere, by executing the loaded program, not only the functions of theaforementioned embodiments are realized, but also by performingprocessing in cooperation with an operating system, other applicationprograms or the like based on an instruction of the program, thefunctions of the invention are realized.

When being distributed in the market, the program is able to be storedin a portable recording medium and distributed or be transferred to aserver computer connected through a network such as the Internet. Inthis case, a storage apparatus of the server computer is also includedin the invention. A part or all of the radio transmission apparatus andthe radio reception apparatus in the aforementioned embodiments may berealized as an LSI which is a typical integrated circuit. Eachfunctional block of a radio transmission apparatus or a radio receptionapparatus may be individually formed into a chip, or a part or allthereof may be integrated and formed into a chip. When each functionalblock is made into an integrated circuit, an integrated circuit controlunit for controlling them is added.

Further, a method for making into an integrated circuit is not limitedto the LSI and a dedicated circuit or a versatile processor may be usedfor realization. Further, in a case where a technique for making into anintegrated circuit in place of the LSI appears with advance of asemiconductor technique, an integrated circuit by the technique is alsoable to be used.

Note that, the invention of the present application is not limited tothe aforementioned embodiments. The radio reception apparatus of thepresent application is not limited to be applied to a mobile stationapparatus, but, needless to say, is applicable to stationary orunmovable electronic equipment which is installed indoors or outdoorssuch as, for example, AV equipment, kitchen equipment, cleaning/washingmachine, air conditioning equipment, office equipment, automatic vendingmachine, other domestic equipment, and the like.

As above, the embodiments of the invention have been described in detailwith reference to drawings, but specific configurations are not limitedto the embodiments, and a design and the like which are not departedfrom the main subject of the invention are also included.

INDUSTRIAL APPLICABILITY

The invention is suitably used for a radio transmission apparatus, aradio reception apparatus, and a communication method.

Note that, the present international application claims priority fromJapanese Patent Application No. 2014-107650 filed on May 26, 2014, andthe entire contents of Japanese Patent Application No. 2014-107650 arehereby incorporated herein by reference.

REFERENCE SIGNS LIST

-   -   1 AP    -   2, 3, 4, 5, 6, 7, 8, 9 STA    -   101, 201 higher layer unit    -   102, 202 control unit    -   103, 203 transmission unit    -   104, 204 reception unit    -   105, 205 antenna    -   1031, 2031 physical channel signal generation unit    -   1032 frame configuration unit    -   1033 control signal generation unit    -   1034, 2032 radio transmission unit    -   1041, 2041 physical channel signal demodulation unit    -   1042, 2043 radio reception unit    -   2042 control information monitoring unit

What is claimed is:
 1. An access point (AP) apparatus configured totransmit data addressed to a plurality of station (STA) apparatuses, theAP apparatus comprising: control circuitry configured to set a frequencyallocation of a plurality of frequency allocations; control signalgeneration circuitry configured to generate first control informationindicating bandwidth and placement in frequency domain, and secondcontrol information indicating the plurality of STA apparatuses; andtransmission circuitry configured to generate a frame including thefirst control information and the second control information, andperform transmission of the frame; wherein the placement in the firstcontrol information and an order of the plurality of the STA apparatusesthat is indicated by the second control information together identify afrequency resource used to transmit data of the plurality of STAapparatuses; the plurality of frequency allocations include either afirst assignment in frequency allocation or a second assignment infrequency domain; a plurality of frequency resources include identicalfrequency bandwidths to each other in the first assignment in frequencydomain; and at least two of the plurality of frequency resources eachexhibit a different frequency bandwidth in the second assignment infrequency domain.
 2. The AP apparatus according to claim 1, wherein theframe including the first control information and the second controlinformation includes information indicating a frequency bandwidth of afirst frequency resource, which is usable for the plurality of frequencyresources each of which exhibit a different frequency bandwidth in thesecond assignment in frequency domain.
 3. The AP apparatus according toclaim 2, wherein the frame including the first control information andthe second control information includes information indicating afrequency in which the plurality of frequency resources are arranged inthe first frequency resource.
 4. The AP apparatus according to claim 1,wherein an order indicating the plurality of radio reception apparatusesthat is indicated by the second control information further indicates anorder of space resources allocated to the plurality of STA apparatuses.5. A station (STA) apparatus that receives a signal that is transmittedfrom an access point (AP) apparatus, the STA apparatus comprising:reception circuitry configured to receive a frame including a firstcontrol information indicating bandwidth and placement in frequencydomain, and a second control information indicating a plurality of STAapparatuses, and the signal in which transmission data addressed to theplurality of STA apparatuses is multiplexed; and control informationmonitoring circuitry configured to identify a frequency resource andtransmission data addressed to the STA apparatus based on the firstcontrol information and the second control information; wherein an orderof the plurality of STA apparatuses that is indicated by the secondcontrol information is identical to an order of the plurality offrequency resources that is indicated by the first control information;the plurality of frequency allocations includes either a firstassignment in frequency allocation or a second assignment in frequencydomain; a plurality of frequency resources include identical frequencybandwidths to each other in the first assignment in frequency domain;and at least two of the plurality of frequency resources each exhibit adifferent frequency bandwidth in the second assignment in frequencydomain.
 6. The STA apparatus according to claim 5, wherein the frameincludes information indicating a frequency bandwidth of a firstfrequency resource, which is usable for the plurality of frequencyresources; and the control information monitoring circuitry identifiesthe frequency bandwidth of the first frequency resource based on theframe.
 7. The STA apparatus according to claim 6, wherein the frameincludes information indicating a frequency in which the plurality offrequency resources are arranged in the first frequency resource; andthe control information monitoring circuitry identifies the frequency inwhich the plurality of frequency resources are arranged, based on theframe.
 8. The STA apparatus according to claim 5, wherein the orderindicating the plurality of STA apparatuses by the control informationfurther indicates an order of space resources allocated to the pluralityof STA apparatuses.
 9. A communication method of an access point (AP)apparatus configured to transmit data addressed to a plurality ofstation (STA) apparatuses, the communication method comprising: settinga frequency allocation of a plurality of frequency allocations;generating first control information indicating bandwidth and placementin frequency domain, and second control information indicating theplurality of STA apparatuses; and generating a frame including the firstcontrol information and the second control information, and performingtransmission of the frame; wherein the placement in the first controlinformation and an order of the plurality of the STA apparatuses that isindicated by the second control information together identify afrequency resource used to transmit data of the plurality of STAapparatuses; the plurality of frequency allocations include either afirst assignment in frequency allocation or a second assignment infrequency domain; a plurality of frequency resources include identicalfrequency bandwidths to each other in the first assignment in frequencydomain; and at least two of the plurality of frequency resources eachexhibit a different frequency bandwidth in the second assignment infrequency domain.